Diagnostic Procedure
WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC TEST REFERENCE - P0868-LINE PRESSURE LOW
| TEST | ACTION | APPLICABILITY |
|---|---|---|
| 1 |
NOTE:
Low fluid level can be the cause of many transmission problems. If the fluid level is low locate and repair the leak then check and adjust the fluid level per the Service Information.
NOTE:
Always perform diagnostics with a fully charged battery to avoid false symptoms. With the DRBIII®, read the engine DTC's. Check and repair all engine DTC's prior to performing transmission symptom diagnostics.With the DRBIII®, read Transmission DTC's. Record all DTC's and 1 Trip Failures.
NOTE:
Diagnose 1 Trip Failures as a fully matured DTC. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test for P0706 CHECK SHIFTER SIGNAL .For Gear Ratio DTC's, check and record all CVI's.Most DTC's set on start up but some must be set by driving the vehicle such that all diagnostic monitors have run.
NOTE:
Verify the flash level of the transmission controller. Some problems are corrected by software upgrades to the transmission controller.
NOTE:
Check for applicable TSB's related to the problem. Perform this procedure prior to Symptom diagnosis.ContinueGo To 2 |
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| 2 | With the DRBIII®, check for other transmission DTC's Is the DTC P0932 present also? Yes --> Refer to the TRANSMISSION CATEGORY and perform the appropriate symptom. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 3 |
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| 3 | With the DRBIII®>, check the STARTS SINCE SET counter for P0868.
NOTE:
This counter only applies to the last DTC set. Is the START SINCE SET COUNTER 2 or less? Yes --> Go To 4 No --> Go To 14 |
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| 4 | Ignition on, engine not running. With the DRBIII®, monitor the Line Pressure, firmly push the Line Pressure Sensor harness connector towards the Transmission. Did the Line Pressure change to about 207 kPa or 30 PSI when the connector was pushed? Yes --> Disconnect and properly reconnect the Line Pressure Sensor connector. Inspect terminals and repair as necessary. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 5 |
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| 5 | Turn the ignition off to the lock position. Remove the Starter Relay.
NOTE:
Failure to remove the Starter Relay can cause a Transmission - No Response condition. Install the Transmission Simulator Miller tool# 8333. With the Transmission Simulator select the "OFF" position on the "Input/Output Speed" switch.
NOTE:
Check connectors - Clean/repair as necessary. Ignition on, engine not running. With the DRBIII®, monitor the Line Pressure during the following step. Using the Transmission Simulator, set the rotary knob to each of the 3 line pressure positions.
NOTE:
All three DRBIII® Line Pressure readings should be steady and +/- 2.0 PSI of the reading specified on the Transmission Simulator. Did the Line Pressure remain steady in all three positions? Yes --> Go To 6 No --> Go To 9 |
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| 6 | Turn the ignition off to the lock position. Install the Line Pressure Adaptor, Miller tool# 8259, and the Pressure Gage, Miller tool# C-3293, 0 to 2000 kPa or 0 to 300 PSI. Start the engine in park. With the DRBIII® monitor the Line Pressure. Monitor the reading on the Pressure Gage Miller tool# C-3293. Compare the Line Pressure readings between the DRBIII® and the Pressure Gage. Is the Line Pressure Gauge reading within 34 kPa or 5 PSI of the DRBIII® reading? Yes --> Go To 7 No --> Replace the Line Pressure Sensor per the Service Information. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . |
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| 7 | Remove and inspect the Transmission Oil Pan for excessive debris per the Service Information. Remove and inspect the Primary Oil Filter per the Service Information.
NOTE:
Make sure the Primary Transmission Oil Filter and/or O-ring is not cracked or split. Does the Oil Pan contain excessive debris and/or is the Primary Oil Filter cracked or plugged? Yes --> Repair the plugged, cracked, or split Primary Transmission Oil Filter and/or O-ring. If the Primary Transmission Oil Filter is plugged refer to the Service Information for the proper Hydraulic repair procedure. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 8 |
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| 8 | If there are no possible causes remaining, view repair. Repair Repair internal transmission problem per the Service Information. Inspect the oil pump per the Service Information and replace if necessary. If no problem is found, replace the Transmission Solenoid/TRS assembly. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . |
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| 9 | Turn the ignition off to the lock position. Disconnect the TCM harness connector. Disconnect the Line Pressure Sensor harness connector.
NOTE:
Check connectors - Clean/repair as necessary. Measure the resistance of the 5-volt Supply circuit from the Line Pressure Sensor harness connector to the TCM harness connector. Is the resistance above 5.0 ohms? Yes --> Repair the 5-volt Supply circuit for an open. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 10 |
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| 10 | Turn the ignition off to the lock position. Disconnect the TCM harness connector. Disconnect the Line Pressure Sensor harness connector.
NOTE:
Check connectors - Clean/repair as necessary. Measure the resistance between ground and the 5-volt Supply circuit. Is the resistance Below 5.0 ohms? Yes --> Repair the 5-volt Supply circuit for a short to ground. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 11 |
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| 11 | Turn the ignition off to the lock position. Disconnect the TCM harness connector. Remove the Transmission Control Relay. Place a jumper wire between the Fused B+ circuit and the Transmission Control Relay Output circuit in the Transmission Control Relay connector. Ignition on, engine not running.
NOTE:
Check connectors - Clean/repair as necessary. Measure the voltage of the 5-volt Supply circuit in the TCM harness connector. Is the voltage above 5.5 volts? Yes --> Repair the 5-volt Supply circuit for a short to voltage. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 12 |
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| 12 | Turn the ignition off to the lock position. Disconnect the TCM harness connector. Disconnect the Transmission Solenoid/TRS harness connector. Remove the Transmission Control Relay from the PDC.
NOTE:
Check connectors - Clean/repair as necessary. Connect a jumper wire between the Fused B+ circuit and the Transmission Control Relay Output circuit in the Transmission Control Relay connector. Ignition on, engine not running. Measure the voltage of the Pressure Control Solenoid control circuit in the TCM harness connector. Is the voltage above 0.5 volts? Yes --> Repair the Pressure Control Solenoid Control circuit for a short to voltage. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Go To 13 |
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| 13 | Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, view repair. Repair Replace the Transmission Control Module per the Service Information. WITH THE DRBIII® PERFORM QUICK LEARN Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . |
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| 14 | The conditions necessary to set this DTC are not present at this time. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit. Wiggle the wires while checking for shorts and open circuits. With the DRBIII®, check the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set. Were there any problems found? Yes --> Repair as necessary. Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 . No --> Test Complete. |
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